//  Browser type and DOM reference methods
var isIE = 0;
var isNav = 0;
var isMac = 0;
var isGecko = 0;
var layerRef="", styleSwitch=""; leftBracket=""; rightBracket="";
var LastActiveCell = 0;
var LastMenuCalled = 0;

//  Determine our browser capabilities
if (document.layers) {
	layerRef = 'document.layers';
	styleSwitch = '';
	leftBracket = '[';
	rightBracket = ']';
	isNav = 1;
	//alert("Netscape!");
}
else if( document.all) {
	layerRef = 'document.all';
	styleSwitch = '.style';
	leftBracket = '[';
	rightBracket = ']';
	isIE = 1;
	//alert("IE!");
}
else if ( document.getElementById ){
	layerRef = 'document.getElementById';
	styleSwitch = '.style';
	leftBracket = '(';
	rightBracket = ')';
	isGecko = 1;
	//alert("Netscape 6!");
}

//  Are we running on a Mac?
if (navigator.platform.indexOf("Mac") != -1){
	isMac = 1;
}

if (isMac){
	 document.write('<style type="text/css">');
	 document.write('<!--');
	 document.write(' BODY, P { ');
	 document.write('    font-size:  10pt;');
	 document.write('}');
	 document.write('//-->');
	 document.write('</style>');
}

//  Homepage billboard information - track what's up
var currLayerID = 0;
var currImgName = "";
var currImgObj = "";

//  Track when images are loaded
var images1Loaded = false;
var images2Loaded = false;

function doLoad() {
	// load the mouseover/active menu graphics
	if (document.images){
		load2('exhibit', 'jpg');
		load2('collection', 'jpg');
		load2('visit', 'jpg');
		load2('events', 'jpg');
		load2('projects', 'jpg');
		load2('osp', 'jpg');
		load2('buyonline', 'jpg');
		load2('newspr', 'gif');
		load2('joinsam', 'jpg');
		load2('newmedia', 'gif');
		load2('search', 'jpg');
		load2('jobs', 'jpg');
		load2('kidpage', 'jpg');
		load2('families', 'jpg');
		load2('teachers', 'jpg');
		load2('rubelbows', 'jpg');
		load2('freestuff', 'jpg');
		load2('behind', 'jpg');
	
		images2Loaded = true;
	}
	return (true)
}

function load2 (imgName, imgFormat) {
	//  Preload images - billboard images (gif or jpg)
	if( document.images ){
		eval( 'm' + imgName + ' = new Image()' )
		eval( 'm' + imgName + '.src = "images2/' + imgName + '.' + imgFormat + '"' )
	}
}

//  Change layer visibility
function hideLayer(layerID){
	var layerName = layerRef + leftBracket + '"' + layerID + '"' + rightBracket;
	if (eval(layerName))
		eval(layerName + styleSwitch + '.visibility="hidden"');
}

function showLayer(layerID){
	var layerName = layerRef + leftBracket + '"' + layerID + '"' + rightBracket;
	if (eval(layerName))
		eval(layerName + styleSwitch + '.visibility="visible"');
}

function sc(layerID) {
	// sc - Swap Color, and update billboard
	if (document.images)
	 {
		//imageSwap(layerID, imgName, imgObj);
		doMagic(layerID, 1);
		currLayerID = layerID;
		//currImgName = imgName;
		//currImgObj = imgObj;
	}
}

function rb(billboardID, currItem, on) {
	// rb - Replace Background
	if (isIE) {
	
		if (on)	currItem.style.color='gray';
		else	currItem.style.color='black';
	}
}

//
//  doMagic - this flips the billboard layers on/off depending upon the
//		  the current mouseover.  It also flips the subnav layers
//		  on/off.  Pretty cool!
//
//  Requires: naming convention for main nav: "m" + number (m1, m2, ... mn)
//		  naming convention for sub nav:  "s" + number (s1, s2, ... sn)
//		  naming convention for central:  "b" + number + 'a' and "b" + number + 'b'
//							(b1a, b1b, b2a, b2b, .... bna, bnb)
//		  naming convention for sub-central: "c" + number + 'a'
//							(c1a, c1b, c1d, ... c2a, c2b,....)
//
function doMagic(divName, over) {
	var baseStr = "";
	
	if(divName.search('m') == 0) {			// Flipping over main menu items
		// Turn off the prior sub-nav layer, and enable the current sub-nav layer.
		if (over && divName != currLayerID){
			if (currLayerID != ""){
				//turn off the prior billboard and subnav layers
				hideLayer(currLayerID.replace(/m/, "s"));
				if(LastMenuCalled != 0)
					LastMenuCalled.className='nav';		    
				baseStr = currLayerID.replace(/m/, "b");
				if (images2Loaded) {
					hideLayer(baseStr + 'a');	// main image
					hideLayer(baseStr + 'b');	// secondary image
					if (baseStr == "b3" )		// *sigh* always an exception...
						hideLayer(baseStr + 'd');
				}
				hideLayer(baseStr + 'c');		// text
			}
			showLayer(divName.replace(/m/, "s"));
		}
			
		// Turn off the prior central layer and enable the current central layer
		if (over) {
			baseStr = divName.replace(/m/, "b");
			if (images2Loaded) {
				showLayer(baseStr + 'a');		// main image
				showLayer(baseStr + 'b');		// secondary image
				if (baseStr == "b3" )		// *sigh* always an exception...
					showLayer(baseStr + 'd');
			}
			showLayer(baseStr + 'c');		// text
		}
	}
}